Nearly all communications systems rely on some form of error control for managing errors that may occur due to noise and other factors during transmission of information through a wireless communication channel. Such communications systems can include satellite systems, fiber-optic systems, and cellular systems. Efficient error control schemes implemented at the transmitting end of these communications systems have the capacity to enable the transmission of data including audio, video, text, etc., with very low error rates within a given signal-to-noise ratio (SNR) environment. Powerful error control schemes also enable a communication system to achieve target error performance rates in environments with very low SNR, such as in satellite and other wireless systems, where noise is prevalent and high levels of transmission power are costly, if even feasible.
Accordingly, a broad class of powerful error control schemes have emerged, which enable reliable transmission of information including convolutional codes, low density parity check (LDPC) codes, and turbo codes. The current digital video broadcast DVB-S2 standard benefits from adaptive coding and modulation (ACM) for improving the bandwidth efficiency, and includes a physical layer signaling code (PLS Code), which yields PLS Codes in the header of the physical frame. DVB-S2 PLS Codes are encoded using (7,64) Reed-Muller codes. This current DVB-S2 PLS coding scheme, however, results in a PLS Code of a number of information bits that limits the information that can be conveyed by the code. While the current limits of the DVB-S2 PLS Code may be sufficient for the current DVB-S2 standard, the current DVB-S2 PLS Code lacks capabilities to support expansion for future systems and future generations of the DVB-S2 standard.
In current systems, outroutes are typically in the order of 30 to 45 Msps over which coded modulation data is sent. In next generation, high capacity satellite systems (e.g., systems of capacities exceeding 100 Gbps), however, bandwidth of outroutes are in the order of greater than 200 Msps (e.g., 220 Msps). While, the current DVB-S2 standard may be applied to a 200 Msps outroute, such application raises a significant challenges in the development of relatively low complexity and low cost ASICs for the demodulation and decoding of such outroutes at the satellite terminals and gateways. In order to address such cost and complexity issues, multiplexing schemes may be employed to reduce the speed at which such ASICs are required to process received data streams, and to reduce complexity and power requirements (hence reducing the costs associated with the decoder ASICs). Such multiplexing schemes entail the multiplexing of a number of lower throughput outroute streams into one larger outroute transmission stream. Thus, because a particular terminal is not intended to consume the entire information bandwidth of the multiplexed stream, the multiplexing scheme allows the decoder to be run at a lower speed and provide the needed information bandwidth. In order to facilitate operation of the decoder at a lower speed, however, the packets of the transmission stream must be coded to permit identification of the packets of a data stream destined for a particular terminal without requiring the terminal to fully demodulate and decode every packet. The current DVB-S2 PLS coding scheme, however, lacks the capability to support such additional coding in the PLS Code, and thus additional layers of coding and decoding would be required.
What is needed, therefore, is a method and apparatus for convolutional coding for DVB-S2 PLS coding to provide an expanded PLS Code (e.g., to support multi-carrier multiplexing within a wideband transponder of a wireless communications system).